Method for fabricating thin film pattern, liquid crystal display panel and method for fabricating thereof using the same

ABSTRACT

A method of fabricating a thin film pattern according to an embodiment of the present invention comprises forming an organic material pattern on a substrate, forming a metal material of liquid phase on a substrate provided with the organic material pattern, hardening the metal material of liquid phase, and removing the metal material located on the organic material pattern, allowing some metal material to be left at an area non-overlapped with the organic material pattern.

This application claims the benefit of Korean Patent Application No.P2006-087383, filed in Korea on Sep. 11, 2006, which is herebyincorporated by reference.

FIELD

The present invention relates to a method of fabricating a thin filmpattern, and a liquid crystal display panel and a fabricating methodthereof using the same that are adaptive for simplifying a process offorming a thin film pattern to reduce fabrication cost and time, and forforming a thin film pattern at an appropriate position to improvereliability and prevent defects.

BACKGROUND

Display devices have become very important as a visual informationcommunicating media in an information society. Cathode Ray Tube (CRT)display devices, which have been the main stream of the display devices,have problems, such as heavy weight and bulky volume.

Flat panel display devices include a liquid crystal display device(hereinafter, referred to as “LCD”), a field emission display(hereinafter, referred to as “FED”), a plasma display panel(hereinafter, referred to as “PDP”), and an electro-luminescence(hereinafter, referred to as “EL”), and the like. Most of these flatpanel display devices are put to practical use, having significantmarket share in the display device market.

Such flat panel display devices include a plurality of thin filmpatterns, and each of the thin film patterns is formed by aphotolithography process and an etching process.

FIG. 1 is a diagram illustrating a technique for forming a thin filmpattern using the photolithography process and the etching process stepby step.

First, a metal layer 4 a is formed on a substrate for a flat paneldisplay device 2 by a deposition technique such as sputtering, and thelike. Next, the photolithography process including a photo-resistcoating, an exposure, and developing processes is carried out to providea photo-resist pattern 5. The metal layer 4 a that did not overlap thephoto-resist pattern 5 is removed by a dry or wet etching process usingthe photo-resist pattern 5 as a mask. Then, the photo-resist pattern 5is removed by a stripping process to form a first thin film pattern 4.

A plurality of thin film patterns are disposed by the photolithographyprocess, and the thin film patterns are electrically connected to eachother or electrically insulated with each other by an electric contactof each of the thin film patterns as occasion demands. Herein, if eachof the metal thin film patterns is electrically insulated, an insulatingfilm 6 is formed on the substrate 2 provided with the first thin filmpattern 4 as shown in FIG. 2. In this case, the insulating film 6 isformed of an inorganic insulating material such as SiN_(x) and the likeby a deposition technique such as PECVD, and the like.

On the other hand, if a gate pattern such as a gate electrode and a gateline, etc is formed at a liquid crystal display panel by thephotolithography process and the etching process in FIG. 1, the wetetching process is used. However, the wet etching process is a methodthat a metal is exposed to an etchant to be selectively removed. Thethin film pattern formed by the wet etching process has a drawback of alarge error and deviation because time adjustment is difficult.Accordingly, if the gate pattern is formed by the wet etching process,the gate pattern is inadequately formed from time to time. As a result,when the liquid crystal display panel is complete, and then an image isrealized, the gate pattern is not formed at the right position togenerate a light leakage problem. Furthermore, although an insulatingfilm is disposed, a step coverage generated by the gate pattern ismaintained as it is. Thus, the data line provided on an insulating filmmay be broken by such step coverage.

The photolithography process and the etching process in FIG. 1 includethe stripping process to remove the photo-resist pattern after theexposure process, the developing process, and the etching process arecarried out. As a result, a manufacturing cost forming a thin filmpattern is increased and a manufacturing time is also increased.

SUMMARY

A method of fabricating a thin film pattern according to an embodimentof the present invention comprises forming an organic material patternon a substrate, forming a metal material of liquid phase on a substrateprovided with the organic material pattern, hardening the metal materialof liquid phase, and removing the metal material located on the organicmaterial pattern, allowing some metal material to be left at an areanon-overlapped with the organic material pattern.

A liquid crystal display panel according to one embodiment of thepresent invention comprises a gate pattern that includes a gate line anda gate electrode connected to the gate line on a substrate, an organicgate insulating film disposed on a substrate provided with the gatepattern, and a data line that crosses the gate line with the organicgate insulating film disposed therebetween. The liquid crystal displaypanel further comprises a thin film transistor provided at a crossing ofthe data line and the gate line, a pixel electrode connected to the thinfilm transistor, and an organic material pattern disposed between thesubstrate and the organic gate insulating film, and located at an areaother than the gate pattern.

A method of fabricating a liquid crystal display panel according toanother embodiment of the present invention comprises forming an organicmaterial pattern on a substrate, and forming a gate pattern thatincludes a gate electrode and a gate line connected to the gateelectrode at an area non-overlapped with the organic material pattern.The method of fabricating a liquid crystal display panel furthercomprises forming an organic gate insulating film on the organicmaterial pattern and the gate pattern, forming a data line that crossesthe gate line, and a thin film transistor located at a crossing of thegate line and the data line with the organic gate insulating filmdisposed therebetween, and forming a pixel electrode connected to thethin film transistor.

A liquid crystal display device comprises a liquid crystal displaypanel. The liquid crystal display panel comprises a gate pattern thatincludes a gate line and a gate electrode connected to the gate line ona substrate, an organic gate insulating film disposed on the substrateprovided with the gate pattern, a data line that crosses the gate linewith the organic gate insulating film disposed therebetween, and a thinfilm transistor provided at a crossing of the data line and the gateline. The liquid crystal display panel further comprises a pixelelectrode connected to the thin film transistor, and an organic materialpattern disposed between the substrate and the organic gate insulatingfilm, and provided at an area other than the gate pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects of the invention will be apparent from thefollowing detailed description of the embodiments of the presentinvention with reference to the accompanying drawings, in which:

FIG. 1 is a process flow chart illustrating a process of fabricating athin film pattern by a photolithography process and an etching processstep by step;

FIG. 2 is a diagram illustrating a condition that an insulating film isformed on a substrate provided with a thin film pattern;

FIG. 3A to FIG. 3C are flow charts illustrating a method of fabricatinga thin film pattern according to an embodiment of the present invention;

FIG. 4 is a diagram illustrating a condition that an organic insulatingfilm is formed on the thin film pattern provided by FIG. 3A to FIG. 3C;

FIG. 5 is a plan view illustrating a thin film transistor arraysubstrate of a liquid crystal display panel according to the embodimentof the present invention;

FIG. 6 is a sectional view of the thin film transistor array substratetaken along the I-I′ line in FIG. 5; and

FIG. 7A to FIG. 7E are process flow charts illustrating the process offabricating the thin film transistor array substrate in FIG. 6 step bystep.

DETAILED DESCRIPTION

Hereinafter, the preferred embodiments of the present invention will bedescribed in detail with reference to FIG. 3A to FIG. 7E.

FIG. 3A to FIG. 3C are process flow charts illustrating a method offabricating a thin film pattern according to an embodiment of thepresent invention.

First, a substrate 102 is provided, and then a photosensitive organicmaterial such as a photo-acryl and the like is coated on the substrate102. Next, an organic material pattern 115 is formed on the substrate102 by a photolithography process including an exposure and developingprocesses as shown in FIG. 3A.

A metal material 118 a of liquid phase is coated on the substrate 102provided with the organic material pattern 115 by the spray method orthe spin coating method. Accordingly, the metal material 118 a of liquidphase is directly located on the substrate 102 and the metal material118 a of liquid phase is partially located on the organic materialpattern 115 as shown in FIG. 3B. Next, the metal material 118 a ofliquid phase is hardened by the dry process.

Herein, the metal material of liquid phase is comprised of silvernitrate AgNO₃, a reducing agent, a material for protecting a metalparticle, and a solvent. Sodium borohydride NaBH₄ may be used as thereducing agent, and polyacrylic ammonuim salt may be used as thematerial for protecting the metal particle.

Next, the metal material 118 a located on the organic material pattern115 is removed by the dry etching process or an ashing process. On theother hand, the metal material 118 a directly provided on the substrate102 as well as the metal material 118 a located on the organic materialpattern 115 are partially removed by the dry etching process. Thus, themetal material 118 a directly located on the substrate 102 has arelatively low thickness before the dry etching process is carried out.Accordingly, a thin film pattern 118 can be formed at an area except forthe organic material pattern 115 as shown in FIG. 3C.

Such a method of fabricating the thin film pattern omits the strippingprocess to remove a related art photo-resist pattern, so that themanufacturing cost and time can be reduced.

Furthermore, the thin film pattern can be provided without the wetetching process, so that a problem generated by carrying out a relatedart wet etching process can be prevented beforehand. In other words, anerror and a deviation are highly decreased by the dry etching process toallow the thin film pattern to be formed at the appropriate position,compared to the thin film pattern formed by the wet etching process.

As described above, the thin film pattern 118 is formed on thesubstrates 102, and then the organic insulating film 122 is formed asshown in FIG. 4. Unlike an inorganic insulating film, the organicinsulating film 122 is formed of an organic material by a spin coatingmethod to offset step coverage between the thin film patterns.Accordingly, thin films are not broken. In this case, the thin films areformed after providing the organic insulating film 122.

Hereinafter, a thin film transistor array substrate of a liquid crystaldisplay panel and a fabricating method thereof will be described withreference to FIG. 5 to FIG. 7E. In this case, the liquid crystal displaypanel is formed by use of the above-mentioned method of fabricating thethin film pattern.

FIG. 5 is a plan view illustrating a thin film transistor arraysubstrate of a liquid crystal display panel according to one embodimentof the present invention, and FIG. 6 is a sectional view of the thinfilm transistor array substrate taken along the I-I′ line in FIG. 5.

Referring to FIG. 5 and FIG. 6, the thin film transistor array substrateincludes a gate pattern disposed on a lower substrate 242, an organicmaterial pattern 230 disposed at an area other than an area where thegate pattern is disposed on the lower substrate 242, an organic gateinsulating film 244 disposed on the gate pattern and the organicmaterial pattern 230, a data line 204 that crosses a gate line 202 withthe organic gate insulating film 244 disposed therebetween, a thin filmtransistor 206 disposed at a crossing of the gate line 202 and the dataline 204, a pixel electrode 218 disposed at a cell area defined by thegate line 202 and the data line 204 and connected to the thin filmtransistor 206, and a storage capacitor 220 disposed at an overlappingarea of the pixel electrode 218 and the pre-stage gate line 202.

The gate pattern includes a gate electrode 208 of the thin filmtransistor 206 and the gate line 202 connected to the gate electrode208, and the organic material pattern 230 is formed at an areanon-overlapped with the gate pattern.

An organic material is coated by the spin coating method to form theorganic gate insulating film 244. Such an organic gate insulating filmoffsets step coverage between the gate pattern and the organic materialpattern 230 which have a different thickness. Furthermore, the organicgate insulating film 244 electrically separates the gate line 202 fromthe data line 204.

The thin film transistor 206 includes the gate electrode 208 connectedto the gate line 202, a source electrode 210 connected to the data line204, a drain electrode 212 connected to the pixel electrode 218, and anactive layer 214 overlapped with the gate electrode 208 and forming achannel between the source electrode 210 and the drain electrode 212.The active layer 214 is overlapped with the data line 204, the sourceelectrode 210, and the drain electrode 212. Furthermore, the activelayer 214 includes a channel portion between the source electrode 210and the drain electrode 212. An ohmic contact layer 248 in ohmic contactwith the data line 204, the source electrode 210, and the drainelectrode 212 is further formed on the active layer 214. Herein, theactive layer 214 and the ohmic contact layer 248 refer to as asemiconductor pattern 247.

The thin film transistor 206 allows a pixel voltage signal applied tothe data line 204 to be charged into the pixel electrode 218 and be keptin response to a gate signal applied to the gate line 202.

The pixel electrode 218 is connected, via a contact hole 216 passingthrough a protective film 250, to the drain electrode 212 of the thinfilm transistor 206. The pixel electrode 218 generates a potentialdifference with respect to a common electrode provided at an uppersubstrate (not shown) by the charged pixel voltage signal. Thispotential difference rotates a liquid crystal located between the thinfilm transistor array substrate and the upper substrate owing to a ∈anisotropy and transmits a light inputted, via the pixel electrode 218,from a light source (not shown) toward the upper substrate.

The storage capacitor 220 is formed by the pre-stage gate line 202 andthe pixel electrode 218. The organic gate insulating film 244 and theprotective film 250 are located between the gate line 202 and the pixelelectrode 218. The storage capacitor 220 allows the pixel voltagecharged in the pixel electrode 218 to be stably maintained until thenext pixel voltage is charged.

The gate pattern including the gate line 202 and the gate electrode 208is formed at the thin film transistor array substrate. In this case, thegate pattern is formed by the method of fabricating the thin filmpattern illustrated in FIG. 3A to FIG. 3C. Accordingly, the strippingprocess to remove the photo-resist pattern can be omitted, so that anentire manufacturing cost and time of the thin film transistor can bereduced.

Furthermore, the gate pattern is not formed by the wet etching process,so that an error and a deviation can be reduced compared to a thin filmpattern provided by the related art wet etching process. As a result,when the liquid crystal display panel is completed to realize an image,the gate pattern is formed at the appropriate position, so that thelight leakage problem is prevented.

The present invention applies the organic gate insulating film 244 toremove step coverage generated by the gate pattern. As a result, a breakor a defect of the data line 204 and the like provided on the organicgate insulating film 244 can be prevented.

Hereinafter, a method of forming the thin film transistor arraysubstrate in FIG. 6 will be described with reference to FIG. 7A to FIG.7E.

Referring to FIG. 7A, the organic material pattern 230, the gateelectrode 208, and the gate line 202 are formed on the lower substrate242 by use of the method illustrated in FIG. 3A to FIG. 3C. In otherwords, the organic material pattern 230 is formed by thephotolithography process, the gate metal material of liquid phase isformed, and the gate metal material located on the organic materialpattern is removed. Accordingly, the gate electrode 208 and the gateline 202 are formed at an area non-overlapped with the organic materialpattern 230.

Referring to FIG. 7B, an organic insulating material such as an acrylicgroup organic compound, BCB, PFCB, or the like is coated on the gatepattern such as the gate electrode 208 and the gate line 202, and theorganic material pattern 230, by use of a method such as the spincoating, and the like. Accordingly, the organic gate insulating film 244is formed on the organic material pattern 230 and the gate pattern.

Herein, a metal material of liquid phase used in FIG. 3A to FIG. 3C maybe used as the gate metal material of liquid phase. In other words, thegate metal material of liquid phase includes silver nitrate AgNO₃ ofabout 10% to about 40%, the reducing agent of about 0.1% to about 3%,the material for protecting metal particle of about 5% to about 20%, andthe solvent of about 40% to about 85%. Sodium borohydride NaBH₄ may beused as the reducing agent, polyacrylic ammonuim salt may be used as thematerial for protecting metal particle, and water may be used as thesolvent.

Referring to FIG. 7C, the active layer 214, the ohmic contact layer 248,and source/drain patterns are sequentially formed on the lower substrate242 provided with the organic gate insulating film 244.

More specifically, an amorphous silicon layer, an amorphous siliconlayer doped with an n⁺ impurity, and the source/drain metal layer aresequentially formed on the lower substrate 242 provided with the organicgate insulating film 244 by the deposition technique such as the PECVD,and the like.

The photo-resist pattern is formed on the source/drain metal layer bythe photolithography process using a mask. In this case, the mask uses adiffractive exposure mask having a diffractive exposure part at thechannel portion of the thin film transistor to allow the photo-resistpattern of the channel portion to have a thickness lower than anothersource/drain pattern portion.

Next, the source/drain metal layer is patterned by the wet etchingprocess using the photo-resist pattern to form the source/drain patternsincluding the data line 204, the source electrode 210, and the drainelectrode 212 being integral to the source electrode 210.

Next, the amorphous silicon layer doped with an n⁺ impurity and theamorphous silicon layer are simultaneously patterned by the dry etchingprocess using the same photo-resist pattern to form the ohmic contactlayer 248 and the active layer 214.

Furthermore, the photo-resist pattern having a relatively low thicknessat the channel portion is removed by the ashing process, and then thesource/drain pattern and the ohmic contact layer 248 of the channelportion are etched by the dry etching process. Accordingly, the sourceelectrode 210 and the drain electrode 212 are electrically separated,and the active layer 214 of the channel portion is exposed. Herein, theohmic contact layer 248 and the active layer 214 are referred to as thesemiconductor pattern 247.

Next, the photo-resist pattern remaining on the source/drain patternportion is removed by the stripping process.

The source/drain metal is formed from Mo, Ti, Ta, Mo alloy, Cu, and anAl-group metal and the like.

On the other hand, the semiconductor pattern 247 may be formed by use ofa separate mask process before forming the source/drain pattern.

Referring to FIG. 7D, the protective film 250 including the contact hole216 is formed on the organic gate insulating film 244 provided with thesource/drain patterns.

The protective film 250 is entirely formed on the organic gateinsulating film 244 provided with the source/drain patterns by thedeposition technique such as the PECVD, and the like. Next, theprotective film 250 is patterned by the photolithography process and theetching process using the mask to form the contact hole 216 exposing thedrain electrode 210 of the thin film transistor 206.

The protective film 250 is made from an inorganic insulating material,or an organic insulating material such as the acrylic group organiccompound having a small dielectric constant, BCB, PFCB, or the like.

Referring to FIG. 7E, the pixel electrode 218 is formed on theprotective film 250.

A transparent electrode material is entirely disposed on the protectivefilm 250 by the deposition technique such as sputtering, and the like.Next, the transparent electrode material is patterned by thephotolithography process and the etching process using the mask to formthe pixel electrode 218. The pixel electrode 218 is electricallyconnected, via the contact hole 216, to the drain electrode 212.Furthermore, an area having a relatively low thickness of the organicgate insulating film 244 and the protective film 250 are formed betweenthe pixel electrode 218 and the pre-stage gate line 202 to comprise thestorage capacitor 220. The transparent electrode material is made fromany one of indium tin oxide (ITO), tin oxide (TO), and indium zinc oxide(IZO).

Herein, the source/drain pattern such as the data electrode 104, thesource and drain electrodes 210 and 212, and the like may also be formedby the method of forming the thin film pattern described in FIG. 3A toFIG. 3C.

Furthermore, the method of fabricating the thin film pattern is notlimited to the liquid crystal display LCD, and may be used for a processof the display devices such as the field emission display FED, theplasma display panel PDP, the electro-luminescence EL, and the like.

As described above, the method of fabricating the thin film patternomits the stripping process to remove the photo-resist pattern, so thatthe manufacturing cost and time can be reduced.

In the liquid crystal display panel and the fabricating method thereofusing the method of fabricating the thin film pattern, the gate patternincluding the gate line and the gate electrode is not formed by the wetetching process, so that an error and a deviation can be highly reducedcompared to a thin film pattern provided by the related art wet etchingprocess. Accordingly, the preset invention forms the thin film patternat the appropriate position to improve reliability of the thin filmpattern, and forms the gate pattern at the appropriate position toprevent a light leakage.

Furthermore, the method according to one embodiment of the presentinvention applies the organic gate insulating film to remove stepcoverage generated by the gate pattern. As a result, a break or a defectof the data line, and the like provided on the organic gate insulatingfilm can be prevented.

Although the present invention has been explained by the embodimentsshown in the drawings described above, it should be understood to theordinary skilled person in the art that the invention is not limited tothe embodiments, but rather that various changes or modificationsthereof are possible without departing from the spirit of the invention.Accordingly, the scope of the invention shall be determined only by theappended claims and their equivalents.

1. A method of fabricating a thin film pattern, the method comprising:forming an organic material pattern on a substrate; forming a metalmaterial of liquid phase on the substrate provided with the organicmaterial pattern; hardening the metal material of liquid phase; andremoving the metal material located on the organic material pattern, andallowing some metal material to be left at an area non-overlapped withthe organic material pattern.
 2. The method of fabricating the thin filmpattern as claimed in claim 1, wherein the metal material of liquidphase is formed by any one of a spray method and a spin coating method.3. The method of fabricating the thin film pattern as claimed in claim1, wherein the reducing agent is sodium borohydride.
 4. The method offabricating the thin film pattern as claimed in claim 1, wherein thematerial for protecting metal particles is a polyacrylic ammonuim salt.5. The method of fabricating the thin film pattern as claimed in claim1, wherein water is used as the solvent.
 6. The method of fabricatingthe thin film pattern as claimed in claim 1, further comprising formingan organic insulating film on the substrate provided with the organicmaterial pattern and the metal material at the area non-overlapped withthe organic material pattern by a spin coating method.